如何解决js父级函数调用子函数出现函数未定义问题

function Locating(locate,time){
        console.log(locate+' -- '+time);
        var p_locate=document.getElementById(locate);
        var window_top_y = document.body.scrollTop;//获取滚动条顶部距离页面顶部的距离
        var element_top_y = p_locate.offsetTop;//获取某元素顶部距离页面顶部的距离
        var distance =   window_top_y-element_top_y;//当前窗口与顶部的距离
        var time = time;
var move_distance = time>50?Math.ceil((distance/Math.ceil(time/50))):distance;//每次移动的距离
        //每次移动的位移应为distance/duration，要移动的位置为element_top_y，
          function pageScroll() {
            var top = document.body.scrollTop;//获取滚动条顶部距离页面顶部的距离
            var dis_top = top - element_top_y;
                window.scrollBy(0,-move_distance);
                scrolldelay=setTimeout('pageScroll()',50);
                if(dis_top<=0){
                    clearTimeout(scrolldelay);
                }
//              console.log(dis_top);
            }
         pageScroll();
    }

 function a(){
        console.log("a")
        function b() {
                console.log("b")
            }
        b()
}

setTimeout('pageScroll()',50)

setTimeout(pageScroll,50);